Spark-plug.



PATENTED 1U Lyin D) B. MILLS. l @SPARK PLUG. AP-PLICTION FILED 0CT.4,1904.'

WILD/mmc s 3331i] ovmclJ zen ofthe United States, residing at 225 Mid L tion shown vin the drawings, Figure 1 is acenf tra] vertical section.

i v is an enlarged View of the, cap before beinCr u `inset, and Fig. 4 is an enlarged section of .bushing before being upset.

v socket-,y and this may be providedwith exinvented certain new and useful Improvements in SparkePlugs, of which the followingv 1s a clear, full, and exact description.

ware shank-such, for. exam lef as porcevsion of the shank when heated would cause the porcelain to 4crack even when a packing material is used.

. inventionillustrated avoids both these ob- `vldlng a gasket between the bushing and the ,lsoft material may be interposed, if desired, to'

f naar arras retrasa oratori.

nAvn) B. MILLS, or vnaar ORANGE, New JERSEY.

ssaakeetue..

Tub. 825,856. y.

specification ef Letters-iraient.

lPatented July 10, 19x16 Application filed October 4,1904. Serial No. 227,125l

Be it known that DAVID B. MILLS, a citi- -landl avenue, East Orange, NewJersey, have My invention relates to a spark-plug; and my object ris to improve and simplify thereonstructlon of the same.

My invention will bel set forth in the claims. In the preferred embodiment of my inven Fig. 2 is a side elevation of the shank, bushing, and cap. Fig. 3

the

Ithas been found that where Aan earthen# lain-is used with an unyie ding bushing screwing down upon a collar on -the same t-here has been great danger 'of cracking the shank, because the pressure when the bush-` ing wa sserewed down too tight or the expan- The embodiment of my jeetions and also avoids the necessity of proeollarof the shank.

ri is a short tubular shell which I call a ternal screw-threads b and a sparking terminal c, if desired. It is also provided with nal, as shown, and an internal l, shoulder p e, which when threads d are internal proiects becel ain or other refractory insulating material,

upon shoulder Ve, where a ring or -gaskete of i form a tight joint, the gasket in this case acting as a part ofthe shoulder vwhich supporte` ,the shank. The shank has a portion h rapen ing upward-that is, away from the-enlargement'. is a threaded bushing surrounding the tapered portion of the shank and screwing' upon the socket, preferably by external threads l thereon, so that the lower edge m lpresses against'said'tapered portion of the shank.

y' The bushing is preferably formed of soft brass, and I` prefer to sharpen o r bevel the edge of the same, as secnin F ig. 4,`so that when the bushingis screwed down this edge-4 thatsia the portion which contacts With' the shafnkJ-will be upset and will turn outward, as'scen in Fi s. 1 and 2. In this Way a close fit will resu t, and even if the' bushing is screwed down too tightly the porcelain will .not be cracked, as the bushing will yield and upset further. kSubstantiallythe same result will occur if the shank expands under-the heat of combustion. The shanlais, furthermore, thicker above the enlargement, and therefore stronger than would be the case if `the sides of thefshank. above the enlargement were parallel/ The shank form'of a wire loated in a hole longitudinally lthrough the shank and, if desired, may have has a head o at. its upper end.A "n is a sparking terminal, preferably in the presses said upset end 79 of conductor n down on. the head 0 of said shank. may be 'fixed in place without the use of ce Thus the vcap ment or solder and produces a good electrical 4 connectionbetween the cap and terminal n. The lower edge 'of the cap is preferably beveled from the outsidetoward the inside, as shown in F ig. 3, whichis an advantage Where the edge is upset in a die., l

i The cap g and terminal are notclairned speeically in this application, asl they are described and claimed in a copending application, Y:serial No. 302,333, filed February 23, 19065,g

It will be observed that the collar formed by the tapered lower end fm, of thebushing, together with the screw-threads upon the bushing and upon the socket, comprises one form of a sealing means for sealing the plug from the escape of gashe two threads being of sullieient length to force the lower edge of the collar against the tapered portion h,- which in the embodiment shown in the drawings is upon the shank/fand so upset the collar. v

l am aware that other forms of ny invention than -that illustrated may be made with i out departing from-the scope of my invention IIO soft metal whereby as claimed, and I therefore do not wish to be limited to the particular embodiment heretoi'oredez-eribed and illust rated, Y

What I claim ishaving a srew-t-hread and 'a shoulder, a

shank of insulating material having thereon l pered portion, the bushing where it presses s portion being formed of it is adapted to be upset o5' said' ressing upon said tapered portion, said bushing being :of a suliicient length to cause such soft-metal portion to be upset.

2. In a spark-plu in combination, a socket having a screwt ead and arshoulder, a shank of insulating materiali having thereon an enlargement adapted torest on said shoulder and tapering upward from said enlargement, and a 'threaded bushing surroundin said tapered ortion and screwing upon said socket and adapted to press against said tapered portion, the lower edge of said bushing being formed of soft metal and adapted to be upset when screwed Adown upon said tapered portion.

3. In a spark-plug in combination, a socket having a screw-thread and a shoulder, a shank ot' insulating material having thereon an enlargement adapted to rest on said shoulder and tapering upward from said enlargement, and a threaded bushing surrounding u p1. n said tapered said tapered portion and screwing upon said pered portion, the lower edge socket and adapted to press against said ta-l being sharpened and formed of soft metal and adapted to be upset when screwed down upon said tapered portion.

1. In a spark-plug in combination, a socket having an internal screw-thread and an interl. In a spark-plug in combination, a socket of said bushing:

upward from said enlargef an enlargement i der and tapering upward l l l. l

nal shoulderprojeeting beyond said threads,

a lshank of insulating material having thereon adapted to rest on said shoulfrom saidenlargement, and an externallv-threaded bushing surrounding said tapere portion and screwing into said socket and adapted to press against said tapered portion, the lower edge of said bushing bein formed of brass and adapted to be upset w )en screwed down u on said tapered portion, a sparking lerminaat the lower end of saidishank, a terminal at the upper end, and a conductor ruiming through said shank. A

5. I n a spark-plug in'r'oinbination, a socket having a screwthread and a shoulder, a shank of insulating material having thereon an enlargement adapted to rest on said shoulder and tapering upward from said enlargement, and a threaded bushing surrounding pered portion, the lower portion of said bushing below the threads thereon being smaller in diameter than said threads and formed of soft metal and adapted to be upset when screwed downupon said tapered portion.

Signed at New York, N. Y., this 30th day of September, 1904.

. DAVID B. MILLS. W'itnesses:

EMnRsoN R. NEWELL, BEATRICE Minvis. 

